Chinese scientists announced Wednesday they have succeeded in changing cells from pigs into embryonic-like stem cells, capable of developing into any type of cell in the body.
The Shanghai Institute of Biochemistry and Cell Biology (SIBCB) of the Chinese Academy of Sciences claimed a global breakthrough in forming pluripotent stem cells using somatic cells (cells that are not sperm or egg cells) from any animal with hooves (ungulates).
Dr. Xiao Lei, heads of the SIBCB stem cell lab, said, "This is the first report in the world of the creation of domesticated ungulate pluripotent stem cells."
It could open the way to creating models for human genetic diseases, genetically engineering animals for human organ transplants, and for developing pigs that were resistant to diseases such as swine flu, he said.
The research team succeeded in generating induced pluripotent stem cells by reprogramming cells taken from a pig's ear and bone marrow.
After the reprogramming factors were introduced via a virus, the cells developed into colonies of embryonic-like stem cells.
Tests confirmed the stem cells were capable of differentiating into the cell types that make up the three layers in an embryo -- endoderm, mesoderm and ectoderm -- a quality of all embryonic stem cells.
The information gained from inducing pluripotent stem cells (iPS cells) would make it much easier for researchers to develop embryonic stem cells (ES cells) that originate from pig or other ungulate embryos.
"Pig pluripotent stem cells would be useful in a number of ways, such as precisely engineering transgenic animals for organ transplantation therapies. The pig species is significantly similar to humans in its form and function, and the organ dimensions are largely similar," said Xiao.
"We could use embryonic stem cells or induced stem cells to modify the immune-related genes in the pig to make the pig organ compatible to the human immune system."
The pigs could be bred as organ donors to provide organs that did not trigger adverse reactions from the patient's own immune system.
Pig pluripotent stem cell lines could also be used to create models for human genetic diseases.
"Many human diseases, such as diabetes, are caused by a disorder of gene expression. We could modify the pig gene in the stem cells and generate pigs carrying the same gene disorder so that they would have a similar syndrome to that seen in human patients. Then it would be possible to use the pig model to develop therapies to treat the disease.
"To combat swine flu, for instance, we could make a precise, gene-modified pig to improve the animal's resistance to the disease. We would do this by first finding a gene that has anti-swine flu activity or inhibits the proliferation of the swine flu virus.
"We can introduce this gene to the pig via pluripotent stem cells -- a process known as gene 'knock-in'. Alternatively, because the swine flu virus needs to bind with a receptor on the cell membrane of the pig to enter the cells and proliferate, we could knock out this receptor in the pig via gene targeting in the pig induced pluripotent stem cell. If the receptor is missing, the virus will not infect the pig."
Xiao said the discovery could also be used to improve animal farming, not only by making pigs healthier, but also by modifying the growth-related genes to change and improve the way they grow.
However, he warned that it could take several years before some of the potential medical applications of the research were in clinical use.
He said the next stage of the research was to use the pig iPS cells to generate gene-modified pigs that could provide organs for people, improve the pig species or be used for disease resistance.
The modified animals would be either "knock in" pigs where the iPS or ES cells have been used to transfer an additional bit of genetic material (such as a piece of human DNA) into the pig's genome, or "knock out" pigs where the technology is used to prevent a particular gene functioning.
The work was published on-line Wednesday in the newly launched Journal of Molecular Cell Biology, an international journal publishing reviews and articles on molecular and cell biology.
(Xinhua News Agency June 3, 2009)
